Pneumatic-valve mechanism.



No, 842,160. PATENTED JAN. 29, 1907.

. B. AIKMAN.

. PNEUMATIC VALVE MECHANISM.

APPLICATION TILED OGT.21, 1905.

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BERT AIKMAN OF PATENT OFFICE.

CHICAGO, ILLINOIS, ASSIGNOR or ONE-HALF To JOHN s. HAMLIN, or CHICAGO, ILLINOIS.

PNEUMATIC-VALVE. MECHANISM.

To all whom it may c0ncerm= Be it known that I, BERT AIKMAN, a citizen of the United $tates, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful'Improvement in Pneumatic-Valve Mechanism, of which the following is a full, clear, concise and exact description, reference being had to the accompanyingdrawings, forming a part of this specification.

.My invention relates to safety attachments for reservoirs containing air under pressure, and is of particular service in connection with air-brake systems, though the invention is not to be restricted to this utility. I

A source of very frequent accidents in rail- Way practice resides in the reduction of the pressure of the air below the point re uired for the effective operation of the air-bra es; and it is the object of my invention to provide a valve which will permit of the escape of some of the air from the tank when the pressure is. reduced below a predetermined minimum, which air in escaping .will operate a guarding device, such as a signal-whistle.-

For this purpose I provide a valve structure which isaclapted when the pressure of the air exceeds a given predetermined minimum to prevent the air from escaping at the valve, butwhen the pressure of-theair is lower than this minimum a limited portion of theair within the reservoir may escape. This air in escaping may be employed in any suitable way for the purpose stated. I desirably cause this air to operate a signal-whistle, so that the engineer or other attendant may at once start the pump to restore suflicient pres-- sure within the reservoir.

While I prefer to operate a signal, I do not wish to be limited to the particularfunction that is performed by the air in escaping. In

I the preferred embodiment of my invention I also include a supplemental device that permits a portion of the air to escape when the pressure has exceeded a given maximum, and this esca ing air may likewise effect an audible signa so that the engineer may stop the pump. It will be seen that in this way effective pressure of the airwithin the reservolr may be constantlymaintained,so that if the air is used in the operation of air-brakes for example,-said brakes need never fail Specification of Letters Patent. Application filed October 21, 1905. Serial No. 283,834.

Patented Jan. 29,1907.

their operation because of insufficient airpressure.

. I will explain my invention more particu-' 'larly by describing the preferred embodiment thereof shown in the drawings, in which Figure 1 is a view of a valve structure, and Fig. 2 is :1. dia rammatic view illustrating the application 0 the invention to an air-brake system.

Referring first to Fig. 2, I have-shown an located on the bottom of an electric car and which is connected with the brake-cylinder 2 by way of the piping 3 and the motormans controlling-valve 4. The valve 5 of my invention communicates with the piping 3 between the elements 1 4.

The base 6 of the valve structure is screwed into the fitting 7, and the cap 8 is screw-threadbetween the base 6 and cap 8, in which a piston or slide 10 is adapted to reciprocate, said piston being seated at 11 upon the base-section to seal the passage 12, that is ada ted to communicate with the chamber 9'an to cut off communication between this passage 12 and the passage 13,that extends to the external air, the passage 12 being in communication with the air-reservoir to make the piston mechanism subject tothe air-pressure. The stem '14 of the piston is of smaller diameter than the piston itself and is normally received Within the reduction 15 of the chamber 9. Some suitable element, as a coiled spring 16, rests upon the pistonnormally to seat the same at the seat or port 11. The spring 16 engages the valve 10, in this instance being directly engaged with the supplemental valve 17, whose being always seated unless the pressure of the air through the passage 12 is excessive.

As I am now describing that portion of my invention that guards against the reduction of the'pressure within the air-reservoir below a predetermined minimum, I will consider in this portion of the, description that the parts 10 [7 are fixed as they normally are, their separation being only eflected ive. When the air exceeds a given minimum pressure, the piston 10 has its upper facein contact with the packing-ring 18, constituting a seat or port, that may be of air-reservoir 1, which may, for example, be

ed upon the base 6. A chamber 9 is afforded function will be later set forth, this valve 17 when the air-pressure in the tank is excessleather, if desired, or said piston may other v gagement of the elements 18 while said pressure exceeds said minimum value, the spring, (which is the preferred instrumental ity for this function,) whoever, exerting sufficient pressure to remove the piston 10 from its seat 18 when the air-pressure is reduced below the lower predetermined limit, whereulpon air will escape from the passage 12 t rough the bore containing the spring 16,

passage 13, and thence to erform its service, this service being in t e instance shown the operation of the whistle 19. For the purpose of enabling the air to pass as last described channels may, if desired, be provided in the base-section 6, through which the air willpass into the passage containing the spring 16 as soon as the piston 10 is removed from its seat 18; but Ido not Wish to be limited to this wayof affording space between the iston and the wall of the piston-chamber. I he descent of the piston 10 is sufiiciently slow to givethe air in escaping through the passage 13 requisite 0 portunity to perform its function. After t e piston has seated itself at 11 the pump may be operated to increase the pressure within the tank, as 1-,. and said piston will not be removed from its seat until the predetermined maximum pressure has been reached, for now the area of the valve structure subject to the air under pressure is limited to the stem 14, which area is therefore considerably less than when the piston 10 is removed from its seat 11.

As soon, however, as a maximum or a predeterm ned higher pressure is reached the return of the piston 10 uponits seat 18 will be very quick,

high ressure.

particularly as compared with the descent of the piston toward its seat 11 under the conditions specified, as a consequence of which rapid return movement of the piston 10 there is no material waste of the air under The spring 16 may be adjuste by the screw-plug 21 to regulate the force exerted by the spring upon the piston 10. Obviously the c oser the coils of the spring the greaterwill be the value of the minimum pressure and the maximum pressure also. If the pump continues its operation after the piston 10 has been restored to its seat 18, it is desirable to guard against an excessive pressure in addition to that required to seat the piston 10 at 18, to which end I employ the su plemental high-pressure valve 17-, normal y resting in a seat afforded inthe piston 10 and working within a 'bore in' said piston, the bore in said piston having communication at 22 with the spaces 12 15, so that the piston or valve 17 will be subject to the pressure of the air passing through the passage 12. When the pressure of t he air is excessive,- thepiston 17 will be raised against the force of the spring 16,

19 as this air finds passage through the bore containin the spring 16 and the duct 13.- In order t at this air may find this passa e, I provide some suitable passage-way, as t e grooves 23:

While I have herein shown and particularly described the preferred embodiment of my inventioml do not wish to be limited to the precise structure shown, as modifications may readily be made therein without departing from the spirit of the invention; but,

Having thus described my invention, I claim as new and desire to secure by Letters Patent- T 1. A structure of the class described including in its formation a slide, a casing within which the slide travels andthrough which passage of air is prevented or permitted'by said slide, two seats or ports of different sizes alternately engaged bythe slide, said slide presenting a comparatively largearea to the air-pressure, when in en agement with one seat, and a smaller area, when in engagement with the other seat, mechanical means tendingvto press the slide toward the latter seat and operating substantially throughout the extent of travel of the slide, and a guardmg device operated b the air that 1s per mltted to escape by t e slide when passing fromthe larger to the smaller seat. 2. A structure of the class described including in its formation a slide, a casing within which the slide travels and through which passage of air is prevented or permitted by said slide, two seats or ports of different sizes alternately engaged by the slide, said slide presenting a comparatively large area to the air-pressure, when in englagement with one seat, and a smaller area, w en in engagement with the other seat, a spring tending to press the slide toward the latters'eat and operating substantially throughout-the extent of travel of the slide, and a guarding device operated by the air that is permitted to escape by the slide when passing from the larger to the smaller seat.

3. A structure of the class described including in its formation a slide, a casing with- I in which the slide travels and through which passage of air is prevented or permitted by said slide, tw0 seats or ports of different sizes vlongitudinally engaged by the-slide, said slide presenting a com aratively large area to the air-pressure, w en in engagement with one seat, and a smaller area, when in engagement with the other seat, mechan ical means tending to press the slidetoward the latter seat, and operating substantially throughout the extent of travel of the slide, regulating Ineansfor adjusting the action of eeaieo said means, and a guarding device operated by the air that is permitted to escape by the slide. when passing from the larger to the smaller seat.

4. A structure of the class described including in its formation a slide, a casing within which the slide-travels and through which passage of air is prevented or permitted by said slide, two seats or ports of different sizes alternately engaged by the slide, said slide presenting a comp aratively large area to the air-pressure, when in engagement with one seat, and a smaller area, when in engagement with the other seat, a spring'tending to press the slide toward the latter seat and operating substantially throughout the ex tent of'travel of the slide, regulating means for adjusting the action of said spring, and a guarding device operated by the air that is ermitted to escape by the slide when passing om the larger to the smaller seat.

5. A structure of the class described in-' cluding in its formation a piston, a casing within which the iston travels and through which assage of mitted y sa1d piston, two seats of different sizes, one at each limit of the travel of the piston, said piston resenting a comparatively large area to t e air-pressure, when in engagement with one seat, and a smaller area, when in engagement with the other seat, mechanical means tending to press the piston toward the latter seat and operating substantially throughout the extent of travel of the slide, a supplemental piston or valve 17 carried by the piston and o erable upon excessive ressure to permit tie escape of air througli said casing, and a guarding device operated by the air that is permitted to escape by the piston when passing from the larger to the smaller seat.

' 6. .A structure of the class described in cluding in its formation a piston, a casing within which the piston travels and through which passage of air is prevented or permitted by said piston, two seats of different sizes, one at each limit of the travel of the piston, said piston resenting a comparatively large area to t e air-pressure, when in engagement with one seat, and a smaller area, when in engagement with the other seat, a spring tending to (press the piston toward t e latter seat an operating sub stantially throughout the extent of travel of the slide, a supplemental piston or valve 17 carried by the piston and operable upon excessive pressure to permit the escape of air through said casing, and a guarding device operated by the air that is permitted to es cape by the piston when passing from the larger to the smaller seat.

7. A structure of the class described including in its formation a slide, a casing within which the slide travels and through which passage of air is prevented or permitted by air is prevented or per said slide, two seats or ports of ditierent sizes alternately engaged by the slide, sa1d slide presenting a comparatively large area to the air-pressure, when in engagement with one seat, and a smaller area, when in engagement with the other seat, mechanical means tending to press the slide toward the latter seat and operating substantially throughout the extent of travel of the slide, and a signal operated b the air that is permitted to escape by the s ide when passing from the larger to the smaller seat.

81. structure of the class described including in its formation a slide, a casingwithin which the slide travels and through which passage of air is prevented or ermitted by Y the slide toward the latter seat and operatin substantially throughout the extent of trave of the slide, and a signal operated by the air that is permitted to escape by the slide when passing from the larger to the smaller seat.

9. A structure of the class described including in its formation a slide, a casing within which the slide travels and through which passage of air is prevented or ermitted by said slide, two seats or ports of itferent sizes alternately engaged by the slide, said'slide presenting a comparatively large area to the air-pressure, when in engagement with one seat, and a smaller area, when in engagement with the other seat, mechanical means tending to press the slide toward the latter seat and operating substantially throughout the extent of travel of the slide, re ulating means cluding in its formation a slide, a casing within which the slide travels and through which passage of air is prevented or ermitted by said slide, two seats or ports of iiferent sizes alternately engaged by the slide, said slide presenting a comparatively large area to the air-pressure, when in engagement with one seat, and a smaller area, when in engagement with the other seat, a spring tending to press the slide toward the latter seat and operatin substantially throughout the extent of trave of the slide, regulating means for adjusting the action of said s ring, and a signal operated by the air that is permitted to escape by the slide when passing from the larger to the smaller seat. v

11. A structure of the class described ted by said piston, two seats of different sizes, one at each limit of the travel of the piston,

said piston presenting a comparatively large means tending to press the piston toward the latter seat and operating substantially throughout the extent of travel of the slide, a supplemental piston or valve 17 carried by the piston and operable upon excessive pressure to permit the escape of air through said casing, a signal operated by the air that is ermitted to escape by the slide When passmg from the larger to the smaller seat, and a guarding device operated by the air that is permitted to escape by the piston when pass- I .mg from the larger to the smaller seat.

12. A structure of the class described including in its formation a piston, a casing Within which the piston travels and through which passage of air is prevented or permit- {ed by said piston, two seats of difierent sizes,

i one at each limit of the travel of the piston, 3 said piston presenting a comparatively large area to the air-pressure, when in en agement with one seat, and a smaller area, w en in engagement With the other seat, a spring tendmg to press the piston toward the latter seat extent of travel of the slide; a supplemental piston or valve 17 carried by the pistomand 0 erable upon excessive pressure to perfnit t 1e esca e of air through said casing, a signal operate by the air that is permitted to escape by the slide when passing from the larger to the'smaller seat, and a iarding device o erated by the piston w on passing from t e "larger to the smaller seat.

In witness whereof I hereunto subscribe G. L. Geese, JOHN S. HAMLIN.

and operating substantially throughout the U 

